{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-91991", "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "state": "PUBLISHED", "assignerShortName": "VulnCheck", "dateReserved": "2026-09-15T11:11:13.311Z", "datePublished": "2026-09-15T15:18:32.408Z", "dateUpdated": "2026-09-15T15:18:32.408Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "shortName": "VulnCheck", "dateUpdated": "2026-09-15T15:18:32.408Z"}, "datePublic": "2026-08-07T00:00:00.000Z", "title": "Tornado before 6.5.8 Cookie Attribute Injection via Capitalized kwargs", "descriptions": [{"lang": "en", "value": "Tornado before 6.5.8 contains an incomplete fix for cookie attribute injection that allows attackers to inject arbitrary cookie attributes by passing capitalized or legacy keyword arguments to set_cookie. Attackers can embed semicolon-delimited data in capitalized parameters like Domain, Path, or SameSite to bypass validation and modify cookie security attributes."}], "problemTypes": [{"descriptions": [{"lang": "en", "description": "Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')", "cweId": "CWE-113", "type": "CWE"}]}], "affected": [{"vendor": "tornadoweb", "product": "tornado", "defaultStatus": "unaffected", "versions": [{"versionType": "semver", "version": "6.5.5", "lessThan": "6.5.8", "status": "affected"}, {"versionType": "semver", "version": "6.5.8", "status": "unaffected"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:tornadoweb:tornado:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.5.5", "versionEndExcluding": "6.5.8"}]}]}], "metrics": [{"cvssV4_0": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N", "attackVector": "NETWORK", "attackComplexity": "HIGH", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "LOW", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "LOW", "subIntegrityImpact": "LOW", "subAvailabilityImpact": "NONE", "baseScore": 6.3, "baseSeverity": "MEDIUM", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "format": "CVSS"}, {"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "NONE", "baseScore": 5.4, "baseSeverity": "MEDIUM"}, "format": "CVSS"}], "references": [{"url": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-wwv5-g3v4-889x", "tags": ["vendor-advisory"], "name": "GitHub Security Advisory (GHSA-wwv5-g3v4-889x)"}, {"name": "VulnCheck Advisory: Tornado before 6.5.8 Cookie Attribute Injection via Capitalized kwargs", "tags": ["third-party-advisory"], "url": "https://www.vulncheck.com/advisories/tornado-before-6.5.8-cookie-attribute-injection-via-capitalized-kwargs"}], "credits": [{"lang": "en", "value": "sec-reex", "type": "reporter"}, {"lang": "en", "value": "arpitjain099", "type": "reporter"}], "x_generator": {"engine": "vulncheck-endgame"}}}}

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "tornado", "vendor": "tornadoweb", "versions": [{"lessThan": "6.5.8", "status": "affected", "version": "6.5.5", "versionType": "semver"}, {"status": "unaffected", "version": "6.5.8", "versionType": "semver"}]}], "source": "disclosure@vulncheck.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Tornado before 6.5.8 contains an incomplete fix for cookie attribute injection that allows attackers to inject arbitrary cookie attributes by passing capitalized or legacy keyword arguments to set_cookie. Attackers can embed semicolon-delimited data in capitalized parameters like Domain, Path, or SameSite to bypass validation and modify cookie security attributes."}], "id": "CVE-2026-91991", "lastModified": "2026-09-16T13:42:49.190", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 5.4, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 2.2, "impactScore": 2.7, "source": "disclosure@vulncheck.com", "type": "Primary"}], "cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "HIGH", "attackRequirements": "PRESENT", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 6.3, "baseSeverity": "MEDIUM", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "LOW", "subIntegrityImpact": "LOW", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "version": "4.0", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "LOW", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "disclosure@vulncheck.com", "type": "Secondary"}]}, "published": "2026-09-15T16:17:58.293", "references": [{"source": "disclosure@vulncheck.com", "url": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-wwv5-g3v4-889x"}, {"source": "disclosure@vulncheck.com", "url": "https://www.vulncheck.com/advisories/tornado-before-6.5.8-cookie-attribute-injection-via-capitalized-kwargs"}], "sourceIdentifier": "disclosure@vulncheck.com", "vulnStatus": "Deferred", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-113"}], "source": "disclosure@vulncheck.com", "type": "Primary"}]}

{"bugzilla": {"description": "tornado: Tornado: Cookie attribute injection via capitalized keyword arguments", "id": "2533964", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2533964"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.4", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N", "status": "draft"}, "cwe": "CWE-915", "details": ["A flaw was found in Tornado. An attacker can bypass security validation in the `set_cookie` function by using capitalized or legacy keyword arguments. This allows the attacker to inject arbitrary cookie attributes, such as `Domain` or `SameSite`, and modify cookie security settings. The consequence is the potential to manipulate cookie behavior, which could lead to unintended security impacts."], "name": "CVE-2026-91991", "public_date": "2026-09-15T15:18:32Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-91991\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-91991\nhttps://github.com/tornadoweb/tornado/security/advisories/GHSA-wwv5-g3v4-889x\nhttps://www.vulncheck.com/advisories/tornado-before-6.5.8-cookie-attribute-injection-via-capitalized-kwargs"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[6.5.5,6.5.8)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "6.5.8"}}], "enrichment": {"confidence": 95.0, "confidence_source": "inferred", "scores": [{"score": 95.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "tornado", "source": "cna", "vendor": "tornadoweb"}, "product": "tornado", "vendor": "tornadoweb"}], "created": "2026-09-15T18:45:18.284654+00:00", "updated": "2026-09-16T02:15:18.220090+00:00", "vendors": ["tornadoweb", "tornadoweb$PRODUCT$tornado"]}